1. Field of the Invention
An object of the invention is a light heat-insulating device comprising elements that reflect radiation, especially infra-red radiation, and a conduction-insulating material, a device that is efficient at high temperatures, i.e. temperatures in the range of at least 800 degrees C.
Owing to its lightness and efficiency, a device of this type can be used especially in aeronautics for heat shielding, but can also be used in many other fields of application where lightness and efficiency are required simultaneously, or else in cases where just efficiency is required
2. Description of the Prior Art
There are known devices of this type in which at least one reflecting screen is interposed between two layers of an insulating material such as quartz wool or mineral wool. The insulating material blocks the transmission of heat by conduction but, owing to its low compactness, it is not opaque to radiation, and this is why reflecting screens are interposed in order to add to the effect of the insulating material. The reflecting screens are, for example, based on a metal having properties that do not deteriorate at working temperatures.
A particular device is known from the French patent delivered under the number 1,545,706, wherein a reflecting screen consists of a sheet of mica coated with a thin layer of gold.
However, these known devices have various disadvantages because, firstly, the screens are relatively heavy, and secondly, depending on the material of which they are made, they are too rigid or too brittle. Consequently, they cannot be used in any configuration whatsoever or under any mechanical stresses whatsoever. Finally, in the particular example of the French Pat. No. 1,545,706, there is an additional disadvantage related to the fact that the sheets of mica, used as a support for the gold, have to be made by splitting and then bonding elementary sheets of mica together before depositing the thin layer. Furthermore, if the reflecting surface has to be too great, several sheets made in this way have to be bonded together before they are coated with gold.
The bonding of mica is a delicate operation. This is because it is necessary to find a bonding material that withstands the working temperature and because, under the influence of vibrations or external stresses, the sheets remain relatively brittle especially if their area is large.
An object of the invention, therefore, is a light heat-insulating device which remains resistant and efficient at high temperatures, regardless of the stresses to which it is subjected.